Observations on Electrical and Chemical Terms. 173 
voured to analyse this salt, I found its component parts inde- 
finitely varying, accordingly as the solution from which it was 
crystallized was more or less concentrated. Since also it is de- 
composed by solution in water, it does not appear that it can be 
considered as a double salt: and it is perhaps only an intimate 
mixture of crystallized particles of the nitrate with those of the 
arseniate of the protoxide of lead. 
Another similar instance has also occurred to me. I had 
mixed together a solution, of muriate of ammonia and ef muriate 
of the oxide of iron, and, having concentrated them, left them to 
crystallize. The salt which | obtained had formed cubes ofa 
fine ruby colour; and upon analysing them, I found only 12 per 
cent. of the oxide of iron. When dissoived in water, they lost 
their colour, and I obtained from the solution first an almost co- 
lourless, and then a light reddish-yellow salt, which in some 
parts was free from any tinge of colour, and in others was un- 
equally coloured, and only of an orange red. Cousequently this 
triple combination is to be considered rather as a mixture, than 
as a true double salt. 
[To be continued. ] 
XXXIII. Observations on Electrical and Chemical Terms. By 
Mr. J. Murray. i 
Colchester, March 4, 1814. 
Sirs,— I THANK you for your prompt insertion of my paper in 
No.189 of the Philosophical Magazine and Journal. — Be pleased 
to supply the word except before “‘ on the latter supposition.” 
In reference to the question of theoretic electricity, | may further 
remark, that it is a solecism in philosophical language, as in logie, 
to use the term negative electricity. To chargea jar with no- 
thing, (for the negation must mean here, as it does in common 
language, an absolute privation,) is incompatible with a correct 
mode of expression, and it happens that this negation exhibits 
powers as active and positive as its antagonist. We cannot 
attribute to a state of rest, the lively character of motion. If 
two powers be intimately blended together (rosin on sulphur and 
red lead), and projected by an elastic gum bottle against a figure 
described by positive electricity, on the ball connected with au 
electric sphere, charged positively, the rosin or inflammable sub- 
Stance will separate from the mass, and ‘adhere to the communi- 
cated electricity; and if negative electricity is the agent em- 
ployed, the metallic oxide willbe the subject of attraction. These 
are experiments familiar to ‘every electrician. In my opinion, 
the same fluid in different quantities should only attract different 
portions of the same substance. 
I see 
